The present invention relates generally to improvements in illumination devices, and it relates particularly to an improved work bench provided with an arrangement which optimally illuminates with a minimum of glare a work piece located in a usual position of the bench work surface.
Unpolarized or ordinary light consists of visible electromagnetic waves having transverse vibrations of equal magnitude in an infinite number of planes, all of which contain the line representing the direction of propagation (light ray).
In explaining the properties of polarized light, it is common to resolve the amplitude of the vibrations of any light ray into components vibrating in two orthogonal planes, each containing the light ray. One of these planes is usually chosen perpendicular to the plane of the visual task and will be referred to herein as the plane of incidence. Accordingly, the two components of light will be referred to as (1) the parallel component or the component in the plane of incidence, and (2) the perpendicular component.
When the parallel component reaches a dielectric visual task, such as a piece of paper, only a small part of it is specularly reflected. To the contrary, a substantial part of a perpendicular component is specularly reflected.
The light specularly reflected at the task increases the luminance (photometric brightness) of both the lightest and darkest parts of the task, in certain viewing directions, thereby reducing its contrast and making it more difficult to see any details.
It was discovered, as the literature makes clear, that the task contrast could be enhanced by eliminating all or part of the perpendicular component, i.e. by polarizing the light in a parallel direction.
Recently, furniture with built-in luminaires has become popular. One arrangement which attempts to provide a satisfactory visual contrast includes, below the fluorescent lamps, a linear polarizer which eliminates the component vibrating in planes parallel to the fluorescent tubes. By mounting the luminaire at or below eye level, the direct glare is eliminated completely. The reflected glare is reduced as long as the observer looks at the work in a plane perpendicular to the fluorescent tubes. However, if the work or task is laterally moved or is angularly shifted to a position, for example, to rotate the viewing angle 45 degrees, the light reaching it will vibrate in a perpendicular plane and, therefore, instead of increasing, it will be reducing the task contrast and increasing the reflected glare.